With the continued proliferation of technology in the daily activities of our society, private user information is commonly input to computing devices, and communicated over networks by these computing devices. For example, merchants commonly install software provided by payment processing services on point-of-sale computing devices to perform transactions with customers using electronic payment instruments. While these types of technological advances greatly increase user satisfaction by allowing transactions with merchants using electronic payment instruments, and increase profits for merchants by receiving payments from users who do not commonly carry non-electronic payment means, there are often security issues with computing devices handling private user information. For example, untrustworthy entities such as hackers may attempt to install versions of software with known security vulnerabilities onto point-of-sale computing devices in order to obtain private information by exposing the known security vulnerabilities. Thus, computing devices which obtain or store private information are vulnerable to attack by hackers who install versions of software with known vulnerabilities.
In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items or features. Moreover, multiple instances of the same part are designated by a common prefix separated from the instance number by a dash. The drawings are not to scale.